Indian generic drug producers will have to wait longer to launch their generic drugs in the US as the Food & Drug Administration (FDA) has lengthened the timeline for granting tentative approval to generic drug applications by 10 months.

Under Paragraph IV of FDA rules, a generic drug producer can file an application to seek approval its generic versions when it believes its product doesn't infringe on patents held by the innovator or it believes that such patents are not enforceable.

In case generic drug producers fail to get tentative approval for their generic versions within this period, they are required to forfeit their exclusive marketing rights for the drug.

The FDA has recently amended its Safety & Innovation Act, increasing the timeframe for giving a provisional approval to such applications filed between Jan. 1, 2010 and Jul. 9, 2012 to 40 months from the previous 30 months.

Industry experts are of the view that the extended time period for approval would lead to delay in the launch of generic version of drugs, which could result into loss of exclusive sales of low-cost drugs.

A pharma research analyst said, "With this delay, companies would run a risk of reduction of the exclusivity period, as the patent may get expired in between, allowing other generic players to enter the market."

The development has raised fear among domestic pharmaceutical companies, such as Ranbaxy, which have a policy to challenge patents.